Wire leaders for blackfin tuna????

Several times, I've been on charters off the Texas coast when we ran
into a school of blackfin tuna, mostly in the 10-30 pound range. What
normally happened was, the crew would throw out a couple handfuls of
sardine chunks, then immediately free-line a whole sardine into the
chum. It would get hit almost instantly, and then they'd hand the rod
to a guest. They used 3 rods at a time; they couldn't have 15 guests
all hooked up at once; it'd be a tangled mess.

The rigs were freelines... just a tuna hook tied directly to the end
of the mono, nothing else.

The problem was, at least half the time the blackfin would bite through
the 50# mono and the crew would have to reel it in, tie on another
hook, etc. They used a HUGE amount of time doing this, sometimes
getting 5 ot 6 biteoffs in a row before finally hooking one.

My question: is there any particular reason why they don't use a fine
wire leader, to prevent so many biteoffs? These tuna were 10-30
pounds, and a 20# leader would be plenty strong and very fine. I don't
know why it wouldn't work, but these guys were seasoned pros, and knew
what they were doing. Any comments out there?

Ron M.